Gecode/R is a Ruby interface to the Gecode constraint programming library. Gecode/R is intended for people with no previous experience of constraint programming, aiming to be easy to pick up and use.

See Gecode::Model to get started.


Gecode/R is still in a development stage, the syntax is by no means final and backwards compatibility will be broken time and time again. Don't use Gecode/R in production-code yet, it's merely available at this point to allow people to play with it and give feedback.


Gecode/R requires Gecode 2.2.0, which can be downloaded from . See for the installation instructions.

Installing from gem

There are two gems. The first includes only Gecode/R, and assumes that you have installed Gecode yourself. The second includes both Gecode/R and Gecode. If you use Windows then you're recommended to use the second one, even though you already have Gecode, as the other one does not come in a pre-compiled variant.

Gecode/R only:

gem install gecoder

Gecode/R and Gecode:

gem install gecoder-with-gecode

Installing from source using gem

rake gem
gem install pkg/gecoder-0.x.x.gem

Installing from source without using gem

“” might have another extension depending on which platform it's generated on (replace the extension in the following commands with whatever extension it's given).

cd ext
ruby extconf.rb
mv ../lib/

Running the tests

rake specs

Requires RSpec (1.0.5, but other version should hopefully work).